1. Field of the Invention
The present invention relates to a process for making a flexographic printing plate.
2. Description of the Related Art
In recent years, as a result of the rapid progress in image processing by computer and various types of high output laser, CTP (computer to plate) processing of printing plates has been advancing rapidly. In flexographic printing plates, a flexographic CTP system has been proposed in which a mask is formed imagewise using a high output IR laser, and this is followed by overall UV exposure and development, thus giving a flexographic printing plate.
However, after the mask-making step, the current flexographic CTP employs the same steps as those of the conventional flexographic plate system from the overall UV exposure onward, and improvement of the productivity, which is the main purpose of CTP, is not satisfactory.
On the other hand, commercially available flexographic CTP plates are complicated sensitive materials with a multilayer structure in which a photosensitive resin is provided on a flexible support such as a polyethylene terephthalate (PET) (this is called a ‘conventional flexographic plate’), and an IR-sensitive layer that is made sensitive to an IR laser so as to form a mask is further provided on the photosensitive resin, and they are expensive compared with conventional flexographic plates. This proposed system also has the problems that an expensive, short-life, high output laser is used, and the IR-sensitive layer, which is removed when forming the mask, must be disposed of as waste.
JP-A-63-109052 (JP-A denotes a Japanese unexamined patent application publication) discloses a process in which an aqueous ink image is applied to a printing plate having a photosensitive resin layer, then exposed, and developed with an aqueous developing agent to give a relief image. German Patent Laid-open No. 417127 discloses a plate material having a transparent top coat layer on a photosensitive recording layer, an image mask being formed on the top coat layer by an ink-jet printer, thus making a plate. JP-A-6-166162 discloses a process for making a seamless flexographic plate by forming an ink-jet mask on a cylindrical plate material, and carrying out exposure and development.